Rudder stops with hydraulic cylinders

Oops I missed that. However it is a drawing to assist in the installation of the components. ie a mechanic would probably not understand hydraulic schematics so the components are numbered so he knows where to put them.

Two pumps and my French = nil, but pompe manuelle sounds like a manual pump. Is it manual or electric motor. Or does manuelle mean you manually switch from one motor to the other ie one motor is a back up motor. Could this be the problem, you have both motors working when you should only have one?

Or is it one of those systems where the pump is attached to the wheel and when you turn the wheel it pumps the oil one way or the other.

The pumps appear reversable so to change the direction of movement of the rudder you reverse the pump direction.

As I suggested on an earlier post 2202022 appears to be a valve that locks the fluid in the cylinders to prevent movement.

What 2202021 is ? Or a badly drawn directional valve and is the dump back to tank. And there are piston rods coming out of both ends of the cylinders which indicates they are centrally located to operate both rudders, so are they two seperate systems, one as a back up?

 

Poida, I would imagine that 2202021 are maybe points to bleed air from the "link" pipe work to both port & stb hulls, 2202022 would be valves to open the piping circuit to allow alignment of rudders/tillers & also possibly allow that link part of the circuit to be "charged" by fluid & that each rudder has its own ram linked by the pipework carrying the link pipe carrying the bleed points 2202021. Regards from Jeff.

 

The chain was a very effective rudder stop that prevented the helmsman being swept overboard if the rudder hit something unforgiving; using wooden stops to protect the cylinders is a bit childish.

The hydraulic steering system being discussed here has little more complexity than a car jack. Oil is manually pumped from left to right and the cylinder's shaft moves accordingly. There are no valves unless it is a dual helm installation.
The car jack uses a tiny oil return hole at the end of the cylinder's stroke so the plunger doesn't pop out if you keep pumping. In a steering system you do not need that because you simply cannot exert that much force.

If the rudder hits a rock, the big question is "what do you want to protect?".
With a solid stop you can avoid forces to be transmitted to the cylinder, but that doesn't do much good when the shaft is bent or the whole rudder falls off. I.m.h.o. the preferred solution is an easy to replace weak link or a coupler that temporarily disengages if a maximum force is exceeded.

 

2202021 are bleeding valves, to purge the system when filling.
2202022 are bypass valves, to fill the system (as the two chambers of the cylinders are not connected), and to allow occasional re-alignement of the rudders.
Manual pumps are hydraulic pumps behind the steering wheel, pushing 40 cc of oil per wheel turn.
RV1 group is the autopilot electric pump, pushing up to 1 liter/min.

 

I didn't realise it was a manual pump attached to the wheel, and as such would agree that the stop should be a physical rudder stop, which would certainly prevent cylinder damage as there are no pressure relief valves.

Although I don't have experience in marine steering hydraulics, I would think that the wheel diameter would have to be limited, to in turn limit the pressure in the system. One would think a big heavy goon hanging off the wheel could do some damage.

 

CDK, you have a very complicated car jack in your car. I've always wanted that, a car jack with auto pilot. Insert the bearings of the flat tyre into your GPS and the jack navigates to the spot.

I didn't even know that any car manufacturer actually made a car jack that fits under a car when it's got a flat tyre.

 

Buy a Kia Sorento, 2009 or older. The jack is behind a small panel in the boot, with a pair of gloves, courtesy of Kia Motors. The car has a real chassis so there is always space for a jack. The autopilot is optional.

 

Steering Principals.

DEar Esprit Marine,

A general point of view on Steering Design noted that the involved devices should be "stand alone" on the possible stresses that could be applied on them.

The Purpose of a Rudder's "Stop" is to define the range and to confine the bounds of the Rudder's Use.

The Rudder could be managed from:
1. Mechanical
2. Hydraulic
3. Electrical
devices that provide the necessary torque to turn it and only that.

The Main purpose of a Hyd. Cylinder is to turn the Rudder and not to push the "Stop" mechanism.

The "Stop" mechanism is just to resist on torque of a "free" moving rudder in case when the Hyd. Cylinder is damaged or is out of order and to avoid getting closer to the Propeller's Blades specially when the vessel moving astern and the rudder is under Propeller's suction.

In case of Sailing yachts a "free" rudder maybe could be cause of a hull dump on rough seas.

On the other hand every Hyd. Cylinder has the design ability to resist 2.5 times to the applied stresses that developed due to its act at full Pressure.

Based to that there is no reason the Rod of the Hyd. Cylinder to act on the Rudder's "Stop" mechanism, but of course is useful to come very close , just to be moved at the most of the range.

These reasons is the base and the corners of the Rudder's matter.

 

A boats steering cylinder is called balanced . The rod/ram comes out both ends , this is so that the same amount of oil to push one way is required to push it the other way.

If it was like a car jack it would not be accurate and confuse the auto pilot electronics.

And if you were to use two rams as push pull you would get binding, --one fighting the other.

In my opinion a rudder stop is a good thing but if on a fibre glass boat strength is the problem to be able to resist the force of a ram, and yet who would try to turn further when a stop was felt.

 

CDK didn't say it was like a car jack Frosty, he said it was no more complicated than a car jack. I don't however agree with either statement.

What you said about the two ended cylinder was interesting and course would have to be true.

In engineering because we use a pump, we balance the cylinder with pressure release valves to reduce the pressure on the piton end.

So I assume then one end of the cylinder has a piston rod that sticks out and does nothing.

 

That is absolutely correct it does nothing but cause a displacement so the cylinder is balanced.

 

Two bottle jacks would make a very cheap, immensely strong steering cylinder that needs no rudder stop at all. But unfortunately at sea they seize after a day or two.

But let's return to the OP's problem.
One way to limit the forces transmitted to the cylinder is to mount the swivel point connecting it to the steering lever between two preloaded coil springs. The piston rod should have a threaded section so with washers and nuts on either side of the springs the load can be adjusted the maximum allowed for the cylinder.
The springs remain at the same length as long as the steering forces are within limits, so do not affect steering precision in any way.

 

CDK, after that suggestion it sounds like you've had a couple of bottles of Jack's.

The only sensible way to set up the hydraulic rudder, is to have the rudder stop and end of cylinder stop occur at the same time.

The spring loaded idea, I would think there would be some fishtailing of the rudder happening as it bounces between the springs.

 

I like the idea, but Jack D. is incredibly expensive in this country.

If both are hard, metallic contacts, the rudder stop and cylinder stop never happen simultaneously. I do not understand the fear of damaging the cylinder's end stops when only a manual pump supplies the power and the displacement ratio is less than 10:1 (I guess it will actually be much less).

I my spring loaded idea, both springs exert a force of say 500 kg on the slider that carries the swivel point; if that would be the maximum allowed load of the cylinder. As long as the forces stay below that threshold, the construction is stable as a rock.

 

steering cable

Hey easy rider do you have your old upper steering cable
and would it be serviceable
looking for a cable,
thank you